Supernova SN2011b? Or not?

[Tim]

That's like the pic I saw Acey. Arms -ish. I'd like to get in deep on that and get some detail but I have swapped to my C9.25 for imaging atm, might take a while at f10 with my skies. I suppose I could put the FR in and get a wider shot. Dont like to keep disturbing the setup though once I settle on a configuration.

It would certainly be nice to see the SN in its proper place in the galaxy, instead of looking like a star in the way of it. Perhaps when it reduces in brightness it will make a more interesting picture.

Cheers

Tim

[Tim]

Arms? It has variously been classified S0 (i.e. no spiral arms), SB0 (barred, no arms) and was catalogued by Arp as having "amorphous spiral arms", i.e. not very distinct. It is also described as a "ring galaxy". Some images do capture the amorphous spiral structure of the outer halo, e.g. this one:

NGC 2655

In that picture there is a very distant edge on galaxy behind 2655 by the look of it, and it is showing on the pics I am currently running. Is it a classfied galaxy does anybody know??

[michael.h.f.wilkinson]

In that picture there is a very distant edge on galaxy behind 2655 by the look of it, and it is showing on the pics I am currently running. Is it a classfied galaxy does anybody know??

I am not sure, but the thing looks like the kind of "tidal stream" you get during merger of galaxies. I am starting up a project with Scott Trager from the astronomy department on automated detection of merging galaxies, so I will ask him what he thinks.

[michael.h.f.wilkinson]

I just got a message from Scott who confirmed that many astronomers assume NGC 2655 has undergone a recent merger. He has not had time to dig up a reference yet, but would have a look.

[acey]

In that picture there is a very distant edge on galaxy behind 2655 by the look of it, and it is showing on the pics I am currently running. Is it a classfied galaxy does anybody know??

NGC 2655 is described as having a small neighbour, UGC 4701, so maybe that's the one - though it looks like it could be a distant background galaxy. Not able to check further right now.

Edit: pretty sure it's a background galaxy, not UGC 4701 which is some way east of NGC 2655.

Edit 2: "Listed in Sloan DSS as USNOA2 1650-01332980 as mag 18.1" [source:http://www.cloudynights.com/ubbthreads/showflat.php/Cat/0/Number/4328014/page/0/view/collapsed/sb/5/o/all/fpart/2/vc/1 ]

[michael.h.f.wilkinson]

NGC 2655 is described as having a small neighbour, UGC 4701, so maybe that's the one - though it looks like it could be a distant background galaxy. Not able to check further right now.

Edit: pretty sure it's a background galaxy, not UGC 4701 which is some way east of NGC 2655.

Edit 2: "Listed in Sloan DSS as USNOA2 1650-01332980 as mag 18.1" [source:Telescope Reviews: Super novae SN 2011B in NGC 2655! ]

Is this a distant background object, or is it in interaction with NGC 2655?

[acey]

I think it must be a background object - it looks like a distant spiral. The object with which NGC 2655 may have merged seems to be the neighbouring dwarf galaxy UGC 4714.

NGC 2655: FROM INNER POLAR RING TO OUTER SHELLS AND TAILS

[michael.h.f.wilkinson]

I think it must be a background object - it looks like a distant spiral. The object with which NGC 2655 may have merged seems to be the neighbouring dwarf galaxy UGC 4714.

NGC 2655: FROM INNER POLAR RING TO OUTER SHELLS AND TAILS

Interesting link, thanks for that. UGC 4714 has not yet merged with NGC 2655 (they are still distinct) but an interaction is going on. This might cause the weird shape of NGC 2655.

[acey]

I haven't read through the paper but the intro says:

"Our maps... show a layer of neutral hydrogen... with a broken streamer of gas trailing off toward the small neighbor galaxy UGC 4714... The complex optical tails and H i dynamics suggest that the galaxy has undergone multiple mergers."

I'm not sure if by "multiple mergers" they mean multiple "collisions" between NGC 2655 and UGC 4714 as they orbit one another, or swallowing up of multiple dwarfs that have lost their identities. But they do seem to be identifying UGC 4714 as a principal culprit in NGC 2655's unusual structure.

[Tim]

Ah, the mystery unravels

I might drop some focal length and spend some time on this one, trying narrowband filters on it too.

There is a large dark area near the core of 2655 on the side of the SN, at first I thought it was a dust mote on the CCD, but it was on the next sub with the galaxy in a different position. Very prominent for a faint galaxy, much more than the dust blobs in M32 for instance.

I'll post a link to the new pic I have of this as soon as I get around to processing it.

Cheers

Tim

[michael.h.f.wilkinson]

I haven't read through the paper but the intro says:

"Our maps... show a layer of neutral hydrogen... with a broken streamer of gas trailing off toward the small neighbor galaxy UGC 4714... The complex optical tails and H i dynamics suggest that the galaxy has undergone multiple mergers."

I'm not sure if by "multiple mergers" they mean multiple "collisions" between NGC 2655 and UGC 4714 as they orbit one another, or swallowing up of multiple dwarfs that have lost their identities. But they do seem to be identifying UGC 4714 as a principal culprit in NGC 2655's unusual structure.

Most galaxies form from multiple mergers of dwarf galaxies. I think UGC 4714 is still in the process of merging with NGC 2655. The merger is not yet complete as the smaller galaxy is still distinct.

[acey]

The paper identifies a "diffuse dwarf" within NGC 2655, seen in their Figure 2 (marked D in top right image), which was previously identified by Karachentseva et al.

CCD and HI observations of LSB dwarf galaxies in the general field.

[michael.h.f.wilkinson]

The paper identifies a "diffuse dwarf" within NGC 2655, seen in their Figure 2 (marked D in top right image), which was previously identified by Karachentseva et al.

CCD and HI observations of LSB dwarf galaxies in the general field.

That is more clearly a recent merger. The peculiar distribution of dust within NGC 2655 noted in the paper is also indicative of recent merger. Very interesting reading!